Patent foramen ovale (PFO) closure device with linearly elongating petals

ABSTRACT

The present invention provides a device for occluding an anatomical aperture, such as an atrial septal defect (ASD) or a patent foramen ovale (PFO). The occluder includes two sides connected by a central tube. In some embodiments, the occluder is formed from filaments that are joined together to define a substantially cylindrical form with openings defining struts. Upon the application of force, the struts deform into loops. The loops may be of various shapes, sizes, and configurations, and, in at least some embodiments, the loops have rounded peripheries. The occluder further includes a catch system that maintains its deployed state in vivo. When the occluder is deployed in vivo, the two sides are disposed on opposite sides of the septal tissue surrounding the aperture and the catch system is engaged so that the occluder closes the aperture.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/395,718, filed Mar. 31, 2006, which is acontinuation-in-part of U.S. patent application Ser. No. 10/890,784,filed Jul. 14, 2004, which claims the benefit of priority to U.S.Provisional Patent Application Ser. No. 60/486,992, filed Jul. 14, 2003,the disclosures of which are incorporated by reference herein in theirentirety.

FIELD OF THE INVENTION

The present invention relates generally to an occlusion device for theclosure of physical anomalies, such as an atrial septal defect, a patentforamen ovale, and other septal and vascular defects.

BACKGROUND OF THE INVENTION

A patent foramen ovale (PFO), illustrated in FIG. 1, is a persistent,one-way, usually flap-like opening in the wall between the right atrium11 and left atrium 13 of the heart 10. Because left atrial (LA) pressureis normally higher than right atrial (RA) pressure, the flap usuallystays closed. Under certain conditions, however, right atrial pressurecan exceed left atrial pressure, creating the possibility that bloodcould pass from the right atrium 11 to the left atrium 13 and bloodclots could enter the systemic circulation. It is desirable that thiscircumstance be eliminated.

The foramen ovale serves a desired purpose when a fetus is gestating inutero. Because blood is oxygenated through the umbilical chord, and notthrough the developing lungs, the circulatory system of the fetal heartallows the blood to flow through the foramen ovale as a physiologicconduit for right-to-left shunting. After birth, with the establishmentof pulmonary circulation, the increased left atrial blood flow andpressure results in functional closure of the foramen ovale. Thisfunctional closure is subsequently followed by anatomical closure of thetwo over-lapping layers of tissue: septum primum 14 and septum secundum16. However, a PFO has been shown to persist in a number of adults.

The presence of a PFO is generally considered to have no therapeuticconsequence in otherwise healthy adults. Paradoxical embolism via a PFOis considered in the diagnosis for patients who have suffered a strokeor transient ischemic attack (TIA) in the presence of a PFO and withoutanother identified cause of ischemic stroke. While there is currently nodefinitive proof of a cause-effect relationship, many studies haveconfirmed a strong association between the presence of a PFO and therisk for paradoxical embolism or stroke. In addition, there issignificant evidence that patients with a PFO who have had a cerebralvascular event are at increased risk for future, recurrentcerebrovascular events. PFO has also been linked to chronic migraineheadaches. Although researchers are still investigating the nature ofthe link, PFO closure has been shown to eliminate or significantlyreduce migraine headaches in many patients.

In certain cases, such as when anticoagulation is contraindicated,surgery may be necessary or desirable to close a PFO. The surgery wouldtypically include suturing a PFO closed by attaching septum secundum toseptum primum. This sutured attachment can be accomplished using eitheran interrupted or a continuous stitch and is a common way a surgeonshuts a PFO under direct visualization.

Umbrella devices and a variety of other similar mechanical closuredevices, developed initially for percutaneous closure of atrial septaldefects (ASDs), have been used in some instances to close ventricularseptal defect (VSDs) and PFOs. These devices potentially allow patientsto avoid the side effects often associated with anticoagulationtherapies and the risks of invasive surgery. However, umbrella devicesand the like that are designed for ASDs are not optimally suited for useas PFO closure devices.

Currently available septal closure devices present drawbacks, includingtechnically complex implantation procedures. Additionally, there are notinsignificant complications due to thrombus, fractures of thecomponents, conduction system disturbances, perforations of hearttissue, and residual leaks. Many devices have high septal profile andinclude large masses of foreign material, which may lead to unfavorablebody adaptation of a device. Given that ASD devices are designed toocclude holes, many lack anatomic conformability to the flap-likeanatomy of PFOs. Thus, when inserting an ASD device to close a PFO, thenarrow opening and the thin flap may form impediments to properdeployment. Even if an occlusive seal is formed, the device may bedeployed in the heart on an angle, leaving some components insecurelyseated against the septum and, thereby, risking thrombus formation dueto hemodynamic disturbances. Finally, some septal closure devices arecomplex to manufacture, which may result in inconsistent productperformance.

The present invention is designed to address these and otherdeficiencies of prior art septal closure devices.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a device for occluding anaperture in septal tissue, including a first side adapted to be disposedon one side of the septal tissue and a second side adapted to bedisposed on the opposite side of the septal tissue. The first and secondsides are adapted to occlude the aperture upon deployment of the deviceat its intended delivery location.

According to some embodiments, the device has an elongated deliveryconfiguration and a shortened deployed configuration. According to someembodiments, the device is generally tubular in the elongated deliveryconfiguration. In some embodiments, the device is formed from a tube.According to some embodiments, the device is formed by cutting the tube.According to other embodiments, the device is formed from a plurality offilaments that are bonded to adjacent filaments at selected locations toform a general tubular profile in an elongated, delivery configuration.Other locations are not bonded and the free portions of the filamentsform the distal and proximal sides, and more particularly, petals in thedistal and proximal sides, that are adapted to occlude the aperture upondeployment of the device.

In some embodiments, the device is designed to cooperate with a catchsystem for holding the device in the deployed configuration. Accordingto some embodiments, the catch system reduces and maintains the axiallength of the device. The catch system can have different constructionsand mechanisms for holding the device in the deployed configuration. Insome embodiments, a catch member that is tubular or elongated isdisposed in an axial passage of the device. The catch member includes acatch mechanism on the proximal end. In one form, catch elements suchas, e.g., balls, attached to a catch element could be used to maintainthe axial dimension of the device. In some embodiments, the particularcatch mechanism could be a screw-type catch, or a flange-type catch, forexample.

According to some embodiments, the device includes a material selectedfrom the group consisting of metals, shape memory materials, alloys,polymers, bioabsorbable polymers, and combinations thereof. Inparticular embodiments, the device includes a shape memory polymer.

According to some embodiments, at least one of the first and secondsides of the device includes a tissue scaffold. According to someembodiments, the tissue scaffold includes a material selected from thegroup consisting of polyester fabrics, Teflon-based materials,polyurethanes, metals, polyvinyl alcohol (PVA), extracellular matrix(ECM) or other bioengineered materials, synthetic bioabsorbablepolymeric scaffolds, collagen, and combinations thereof. In particularembodiments, the tissue scaffold includes nitinol.

According to some embodiments, the first and second sides of the deviceare connected by a central tube. According to some embodiments, thecentral tube is positioned so as to minimize distortion to the septaltissue surrounding the aperture. In particular embodiments, the centraltube is positioned at an angle θ from the second side, and the angle θis greater than 0 degrees and less than about 90 degrees.

In one aspect, the invention provides an occluder for a defect adaptedto be introduced into the body through the vasculature. The occluderincludes an occluder body, with an elongated tubular deliveryconfiguration and a shortened deployed configuration. The occluder has adistal side and a proximal side that cooperate to close the defect inthe deployed configuration when an axial length of the occluder isshortened. The distal side includes a plurality of distal openings thatdefine a plurality of distal struts and the proximal side includes aplurality of proximal openings that define a plurality of proximalstruts. The plurality of distal and proximal struts define a pluralityof distal and proximal loops when the axial length of the occluder isshortened. The loops do not include any cut surfaces.

In certain embodiments, the plurality of openings in the occluder bodyextend parallel to a longitudinal axis of the occluder body. In certainembodiments, adjacent openings are aligned. In certain embodiments, acatch system is adapted to secure the occluder body in the deployedconfiguration such that the occluder is not secured during delivery andbecomes secured during deployment.

In certain embodiments, the occluder further comprises tissuescaffolding attached to the loops. In certain embodiments, the loops onthe proximal side are of different size than the loops on the distalside because of relative lengths of the proximal and distal openings.

In certain embodiments, the occluder body includes a plurality offilaments, and the distal and proximal struts are provided by segmentsof the filaments. In certain embodiments, a first filament has acircular cross-section. In certain embodiments, a first filament has asemi-circular cross-section. In certain embodiments, a first filamentand a second filament have different cross-sections. In certainembodiments, a first filament is coated with a therapeutic or otheragent.

In another aspect, the invention provides an occluder for a defectadapted to be introduced into the body through the vasculature, theoccluder having a proximal side and a distal side that cooperate toclose the defect, the occluder have a delivery configuration and adeployed configuration. The occluder includes a plurality of filamentsextending from a distal end to a proximal end and disposed radiallyaround a longitudinal axis, the plurality of filaments defining ageneral tubular shape in a first configuration. The plurality offilaments form a distal joint, a proximal joint and a center joint,wherein each filament is bonded to a first adjacent filament and asecond adjacent filament at the distal joint, the center joint and theproximal joint. A first portion of each filament has adjacent openingsextending from the proximal joint to the center joint and a secondportion of each filament has adjacent openings extending from the centerjoint to the distal joint. The first portions and second portions of thefilaments form proximal loops and distal loops in a second configurationwhen an axial length of the occluder is shortened.

In some embodiments, a catch system is adapted to secure the occluderbody in the deployed configuration such that the occluder is not securedduring delivery and becomes secured during deployment.

In some embodiments, tissue scaffolding is attached to the loops. Insome embodiments, the proximal loops are of different size than thedistal loops because of the relative lengths of the proximal and distalopenings.

In some embodiments, a first filament has a circular cross-section. Insome embodiments, a first filament has a semi-circular cross-section. Incertain embodiments, a first filament and a second filament havedifferent cross-sections. In some embodiment, a first filament is coatedwith a therapeutic agent. In some embodiments, the loops do not includecut surfaces.

In another aspect, the invention provides an occluder for a defectadapted to be introduced into the body through the vasculature having aproximal side and a distal side that cooperate to close the defect. Theoccluder includes a plurality of filaments extend from a distal end to aproximal end and are disposed in a substantially cylindricalarrangement. Each filament is connected to a first adjacent filament anda second adjacent filament at selected portions. The unconnectedportions of the filaments form distal and proximal loops when the axiallength of the occluder is shortened.

In some embodiments, the loops do not include cut surfaces.

In another aspect, the invention provides a method of making an occluderfor closing a defect in the body that has a proximal side and a distalside that cooperate to close the defect. One step is aligning aplurality of filaments in a cylindrical arrangement. Another step isbonding each of the plurality of filaments to a first adjacent filamentand a second adjacent filament at a proximal end to define a proximaljoint, bonding each of the plurality of filaments to a first adjacentfilament and a second adjacent filament at a distal end to define adistal joint, and bonding each of the plurality of filaments to a firstadjacent filament and a second adjacent filament at a central portion todefine a center joint. Another step is defining distal loops from afirst segment of the plurality of filaments extending from the distaljoint to the center joint and defining proximal loops from a secondsegment of the plurality of filaments extending from the proximal jointto the center joint. In some embodiments, another step is coating atleast one filament with a therapeutic agent prior to the step ofaligning.

According to some embodiments, each of the loops includes a rounded edgeat its periphery to minimize trauma to the septal tissue. In particularembodiments, the outer periphery of the device is circular.

According to some embodiments, a force is applied to each of the firstand second ends in an axial direction such that the axial length of thetube is reduced. The force applied to the first end is in a directionopposite to that of the force applied to the second end. The combinationof forces causes the device to transform to the deployed configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a human heart including variousseptal defects;

FIGS. 2A-2D are isometric views of an embodiment of an occluderaccording to the present invention;

FIGS. 2E-2H are isometric views of an embodiment of an occluderaccording to the present invention;

FIGS. 2I-2K are isometric views of occluders according to variousembodiments of the invention;

FIGS. 2L and 2M are side and top views, respectively, of an alternateembodiment of an occluder according to the present invention;

FIGS. 3A-3C are front elevational, side, and cross-sectional views,respectively, of the occluder of FIGS. 2A-2D;

FIGS. 4A-4B are front elevational and side views, respectively, ofanother embodiment of an occluder according to the present invention;

FIGS. 5A-5B are front and side views, respectively, of still anotherembodiment of an occluder according to the present invention;

FIGS. 6A-6E are isometric views of one embodiment of a catch systemaccording to the present invention;

FIGS. 7A-7C are side views of another embodiment of a locking mechanismaccording to the present invention;

FIGS. 8A-8C are isometric views of yet another embodiment of an occluderaccording to the present invention;

FIGS. 9A-9H are side views of one method for delivering an occluderaccording to the present invention to a septal defect; and

FIGS. 10A-10D are side views of one method for retrieving an occluderaccording to the present invention from a septal defect;

FIG. 11 is a side view of an embodiment of the occluder of the presentinvention;

FIG. 12 is an isometric view of an embodiment of the occluder of thepresent invention;

FIG. 13 is a side view of the occluder of FIGS. 2I-2K deployed in vivo;

FIGS. 14A-D are isometric views of an embodiment of an occluderaccording to the present invention; and

FIG. 15 is a front view of a placement device for forming an occluderaccording to an embodiment of the invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The present invention provides a device for occluding an aperture withinbody tissue. In various embodiments, the device relates particularly to,but is not limited to, a septal occluder made from a tube orsubstantially cylindrical body. In particular and as described in detailbelow, the occluder of the present invention may be used for closing anASD, VSD or PFO in the atrial septum of a heart. Although theembodiments of the invention are described with reference to an ASD, VSDor PFO, one skilled in the art will recognize that the device andmethods of the present invention may be used to treat other anatomicalconditions. As such, the invention should not be considered limited inapplicability to any particular anatomical condition.

FIG. 1 illustrates a human heart 10, having a right atrium 11 and a leftatrium 13 and including various anatomical anomalies 18 a and 18 b. Theatrial septum 12 includes septum primum 14 and septum secundum 16. Theanatomy of the septum 12 varies widely within the population. In somepeople, septum primum 14 extends to and overlaps with septum secundum16. The septum primum 14 may be quite thin. When a PFO is present, bloodcould travel through the passage 18 a between septum primum 14 andseptum secundum 16 (referred to as “the PFO tunnel”). Additionally oralternatively, the presence of an ASD, such as that schematicallyillustrated by aperture 18 b, could permit blood to travel through anaperture in the septum.

The term “bioabsorbable,” as used in this application, is alsounderstood to mean “bioresorbable.”

In this application, “distal” refers to the direction away from acatheter insertion location and “proximal” refers to the directionnearer the insertion location.

Referring to occluder 20, distal side 30 and proximal side 40 areconnected by central tube 22. As illustrated, e.g., in FIGS. 2B and 2Fthe central tube 22 is an uncut central part of the tube used to formoccluder 20. As described below, the entire tube is indicated byreference numeral 25. As shown in FIGS. 9 and 10, the occluder 20 may beinserted into the septal tissue 12 to prevent the flow of blood throughthe aperture 18 a, e.g., the occluder may extend through the PFO tunnelsuch that the distal side 30 is located in the left atrium 13 and theproximal side 40 is located in the right atrium 11. Additionally oralternatively, the occluder 20 may be inserted into the septal tissue 12so as to prevent the flow of blood through the aperture 18 b, e.g., theoccluder may extend through the ASD such that the distal side 30 islocated in the left atrium 13 and the proximal side 40 is located in theright atrium 11. As used in this application, unless otherwiseindicated, the term “aperture 18” refers to any anatomical anomaly thatmay be treated by use of occluder 20, such as PFO 18 a, ASD 18 b or VSD.

The occluder 20 is constructed of one or more metal or polymer tube(s),referred to collectively as “tube” 25. Tube 25 includes slits 31 and 41(or 231 and 241), which are formed using an etching or cutting processthat produces a particular cutting pattern on tube 25. For example, asshown in FIG. 2K, slits 31 (or 231) are cut along the axial length ofthe upper half of tube 25 using a cutting tool, e.g., a razor blade.According to some embodiments of the present invention and as shown inFIG. 2K, slits 31 (or 231) are cut without removing any significantamount of material from tube 25, i.e., the formation of slits 31 (or231) does not significantly reduce the overall volume of tube 25.According to other embodiments of the present invention, slits 31 (or231) are formed by cutting material out of tube 25 such that the volumeof tube 25 is reduced. Both ends of each of slits 31 are rounded so asto relieve stresses at the axial ends of the slits 31. This preventsslits 31 from lengthening due to cyclic stresses present in a beatingheart and the resultant material fatigue. In those embodiments whereslits 31 are cut without removing any significant amount of materialfrom tube 25, rounded ends or holes 33 may be produced by burning holesat both ends of each of slits 31. In those embodiments where slits 31are formed by cutting material out of tube 25, rounded ends 33 may beformed during the cutting process. The size of rounded ends 33 may varydepending upon the dimensions of tube 25 and the amount of stressrelease required by the deformation.

FIGS. 2D and 2H illustrate exemplary occluder 20 formed from a tube 25,according to some embodiments of the present invention. Configuration ofthe occluder 20 is determined by the cutting pattern on tube 25. Forexample, and as shown in FIGS. 2A, 2B-2D, and 3A-3C, petal-shaped loops32, 42 (FIGS. 2A-2D and FIG. 3A) are produced by cutting slits 31 in thedistal side 30 of tube 25, and cutting slits 41 in the proximal side 40of tube 25 according to the cutting pattern shown in FIG. 2A. As shownin FIG. 2B, the distal side 30 of tube 25 is cut in half from a centerportion 22 to a distal distance to form half sections 91 a and 91 b. Thehalf sections 91 a and 91 b are further cut to a proximal distance fromthe distal end 39 into quarter sections 92 a, 93 a, 92 b, and 93 b. Thecuts are discontinued and quarter sections 92 a and 92 b form halfsection 94 a at end 39, and quarter sections 93 a and 93 b form halfsection 94 b at end 39. Upon application of force F_(d) to end 39,struts bow and twist outward to form petal-shaped loops 32 in distalside 30, as shown in FIGS. 2C-2D. The movement of the struts duringdeployment is such that the struts rotate in an orthogonal planerelative to the axis of the device. Central tube 22 may be constrainedduring the application of force F_(d), or any combination of forcessufficient to reduce the axial length of the tube 25 may be applied. Oneend of each of petal-shaped loops 32 originates from central tube 22,while the other end originates from end 39 (FIGS. 2B-2C and FIG. 3A).Petal-shaped loops 42 may be formed in proximal side 40 of tube 25, asshown in FIGS. 2B-2D, using the same cutting pattern described above.

Given that the surface of occluder 20 will contact septal tissue 12 onceit is deployed in vivo, slits 31 and 41 are cut so as to prevent theformation of sharp, potentially damaging edges along their length. Forexample, a heated cutting tool may be used to cut slits 31 and 41 suchthat the material of tube 25 melts slightly when placed in contact withthe cutting tool. Such melting rounds the edges of the sections. Lasersmay also be used to cut slits 31 and 41. According to this process, theedges of loops 32 and 42 formed by the cutting of slits 31 and 41 areblunted (due to melting) to prevent tissue damage in vivo. One skilledin the art will recognize that same considerations and techniques alsoapply to slits 231 and 241.

The tube(s) 25 forming occluder 20 includes a biocompatible metal orpolymer. In at least some embodiments, the occluder 20 is formed of abioabsorbable polymer, or a shape memory polymer. In other embodiments,the occluder 20 is formed of a biocompatible metal, such as a shapememory alloy (e.g., nitinol). The thermal shape memory and/orsuperelastic properties of shape memory polymers and alloys permit theoccluder 20 to resume and maintain its intended shape in vivo despitebeing distorted during the delivery process. In addition, shape memorypolymers and metals can be advantageous so that the structure of thedevice assists in compressing the PFO tunnel closed. Alternatively, oradditionally, the occluder 20 may be formed of a bioabsorbable metal,such as iron, magnesium, or combinations of these and similar materials.Exemplary bioabsorbable polymers include polyhydroxyalkanoatecompositions, for example poly-4-hydroxybutyrate (P4HB) compositions,disclosed in U.S. Pat. No. 6,610,764, entitled PolyhydroxyalkanoateCompositions Having Controlled Degradation Rate and U.S. Pat. No.6,548,569, entitled Medical Devices and Applications ofPolyhydroxyalkanoate Polymers, both of which are incorporated herein byreference in their entirety.

The cross-sectional shape of tube 25 may be circular or polygonal, forexample square, or hexagonal. The slits 31 and 41 (or 231 and 241) maybe disposed on the face of the polygon (i.e., the flat part) or on theintersection of the faces.

The tube 25 can be extruded or constructed of a sheet of material androlled into a tube. The sheet of material could be a single ply sheet ormultiple ply. The slits that form the struts could be cut or stampedinto the tube prior to rolling the tube to connect the ends to form anenclosed cross section. Various geometrical cross sections are possibleincluding circular, square, hexagonal and octagonal and the joint couldbe at the vertex or along the flat of a wall if the cross section is ofa particular geometry. Various attachment techniques could be used tojoin the ends of the sheet to form a tube, including welding, heatadhesives, non-heat adhesives and other joining techniques suitable forin-vivo application.

The surface of tube 25 may be textured or smooth. An occluder 20 havinga rough surface produces an inflammatory response upon contact withseptal tissue 12 in vivo, thereby promoting faster tissue ingrowth,healing, and closure of aperture 18 a (shown in FIG. 1). Such a roughsurface may be produced, for example, by shaving tube 25 to producewhiskers along its surface. For example, central tube 22 may includesuch whiskers. Additionally or alternatively, the surface of tube 25 maybe porous to facilitate cell ingrowth.

The distal side 30 of the occluder 20 (also called the “anchor portion”)is shown in FIGS. 2C and 2D. The distal side 30 includes four loops 32a, 32 b, 32 c, and 32 d (collectively referred to as loops 32). Aspreviously described, each of loops 32 a-32 d are formed bycorresponding cut sections 92 b, 93 b, 92 a, 93 a, produced by cuttingslits 31. The application of force F_(d) to end 39 of tube 25 brings theaxial ends of slits 31 together such that struts bow and twist outwardlyto form loops 32 of distal side 30 (FIGS. 2B-2C). Central tube 22 may beconstrained during the application of force F_(d). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy the distalside 30 of occluder 20.

As illustrated, the loops 32 are evenly distributed about central tube22 and end 39. Thus, when the distal side 30 includes four loops 32 (asshown in FIGS. 2C and 2D), the four slits 31 are spaced 90 degreesradially apart. Similarly, when the distal side 30 includes six loops32, the six slits 31 are spaced 60 degrees radially apart. The anglebetween radially equally-spaced is determined by the formula(360/n_(d)), where n_(d) is the total number of loops 32.

Although the distal side 30 of the occluder 20 shown in FIG. 3A includesfour loops 32, occluders according to the present invention may includeany number of loops 32 necessary for a given application. In particularembodiments, the distal side 30 of occluder 20 includes six loops 32(FIG. 4A). Occluders having between four and ten loops 32 may be formedwithout requiring significant adjustments in the processes described inthis application. However, occluders having less than four or more thanten loops 32 may be complicated to manufacture and difficult deliverthrough the vasculature.

Regardless of the number of loops included in distal side 30 anddepending upon the material used to form occluder 20, the outerperimeter of loops 32 may vary. In at least some embodiments, the outerperimeter of loops 32 is rounded to provide an occluder 20 having asmooth, circular perimeter. As the number of loops 32 in the distal side30 of occluder 20 increases, it becomes desirable to round the outerperimeters of the loops 32 so as to prevent the infliction of trauma onthe surrounding septal tissue 12.

The proximal side 40 of the occluder 20, shown in side view in FIG. 2D,also includes four loops, 42 a, 42 b, 42 c, and 42 d (collectivelyreferred to as loops 42). As previously described, each of loops 42 a-42d are formed by corresponding cut sections, produced by cutting slits41. The application of force F_(p) to tip 44 of tube 25 brings the axialends of slits 41 together such that struts bow and twist outwardly toform loops 42 of proximal side 40 (FIGS. 2C-2D). Central tube 22 may beconstrained during the application of force F_(p). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy theproximal side 40 of occluder 20. As described above for distal loops 32,the loops 42 are evenly distributed about central tube 22 and tip 44.Similarly, the angle between radially equally-spaced slits 41 in theproximal side 40 is determined by the formula (360/n_(d)), where n_(d)is the total number of loops 42.

Although the proximal side 40 of the occluder 20 shown in FIG. 2Dincludes four loops 42, one skilled in the art will recognize that theproximal side 40 of an occluder according to the present invention mayinclude any number of loops 42 required and suitable for a givenapplication. In particular embodiments, the proximal side 40 of occluder20 includes six loops 42 (FIG. 4A). Further, although as illustrated,distal side 30 and proximal side 40 both include four loops, there is norequirement that distal side 30 and proximal side 40 of occluder 20include the same number of loops. In fact, in particular applications,it may be advantageous to use an occluder 20 in which the distal side 30contains fewer loops than the proximal side 40, or vice versa.

It will be apparent to one skilled in the art that loops 32 and loops 42(or loops 232 and 242) do not have to be the same size, although theycould be in some embodiments. In one embodiment, loops 32 (or 232) arelarger in size than loops 42 (or 242). In another embodiment, loops 32(or 232) are smaller in size than loops 42 (or 242). Size of loops 32and 42 (or 232 and 242) is determined by the lengths of slits 31 and 41(or 231 and 241), respectively. Therefore, absolute and relative lengthsof slits 31 and 41 (or 232 and 241) can be varied to achieve desiredabsolute and relative sizes of loops 32 and 42 (or 232 and 242).

In at least some embodiments, illustrated in FIG. 4A, loops 42 of theproximal side 40 are radially offset from loops 32 of the distal side 30to provide a better distribution of forces around the aperture 18 a.This can be achieved by making cuts to create slits 31 and 41 such thatthey are radially offset relative to each other. The maximum degree ofoffset will depend on the number of slits. In general, if slits areequally spaced, the maximum possible offset will be one half of theangle between the loops. For example, if distal side 30 (or proximalside 40) contains 4 slits (and therefore 4 loops), loops will be 90degrees apart (see the formula described above), thereby allowing formaximum degree of offset of one half of 90 degrees (which is 45 degrees)between loops 32 and loops 42. In a preferred form, when distal side 30(or proximal side 40) contains 4 slits (and therefore 4 loops), loops 42and loops 32 are offset by 45 degrees. In an alternative embodiment, thedegree of offset between loops 32 and 42 ranges from about 30 to about45 degrees.

FIGS. 2E-2H illustrate another embodiment of the invention, where theoccluder 20 is formed from a tube with loops 232 and 242, produced fromthe cutting pattern shown in FIG. 2E. In one embodiment, the proximalside 40 and the distal side 30 of occluder 20 each include eight loopsor petals. As shown in FIG. 2E, the distal portion 30 of the tube 25includes 8 slits 231 that form 8 extended segments of the tube that formthe distal loops or petals 232. As apparent from the figures, the slitsextend the entire distance of the distal portion 30 of the tube 25, i.e.between central tube 22 and distal end 39, so that the loops ofidentical cross-sections are formed. Upon application of force F_(d) todistal end 39, extended segments defined by slits 231 bow and twistoutward to form distal petals 232 in distal side 30 of the occluder 20.The movement of the segments during deployment is such that the segmentsrotate in an orthogonal plane relative to the axis of the device.Central tube 22 may be constrained during the application of forceF_(d), or any combination of forces sufficient to reduce the axiallength of the tube may be applied. One end of each of distal petals 232originates from central tube 22, while the other end originates fromdistal end 39. Proximal petals 242 may be formed in proximal portion 40,as shown in FIGS. 2E-2H, making slits 241 between central tube 22 andproximal tip 44, using the same cutting pattern described above andapplying force F_(p) or combination of forces sufficient to reduce theaxial length of the tube by allowing slits 241 to bow and twist outwardto form proximal petals 242 in proximal portion 40 of the occluder 20.One end of each of proximal petals 242 originates from central tube 22,while the other end originates from proximal tip 44.

One embodiment of the distal side 30 of the occluder 20 (also called the“anchor portion”) is shown in FIGS. 2G and 2H. The distal side 30includes eight loops 232 a, 232 b, 232 c, 232 d, 232 e, 323 f, 232 g,and 232 h (collectively referred to as loops 232). As previouslydescribed, each of loops 232 a-232 h is produced by cutting slits 231.The application of force F_(d) to end 39 of tube 25 brings the axialends of slits 231 together such that struts bow and/or twist outwardlyto form loops 232 of distal side 30 (FIGS. 2F-2G). Central tube 22 maybe constrained during the application of force F_(d). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy the distalside 30 of occluder 20.

As illustrated, the loops 232 are evenly distributed about central tube22 and end 39. Thus, when proximal side 30 includes eight loops 232 (asshown in FIGS. 2G and 2H), the eight slits 231 are spaced 45 degreesradially apart. The angle between radially equally-spaced slits 231 indistal side 30 is determined by the formula (360/n_(d)) where n_(d) isthe total number of loops 232.

The proximal side 40 of the occluder 20, shown in side view in FIG. 2H,also includes eight loops, 242 a, 242 b, 242 c, 242 d, 242 e, 242 f, 242g, and 242 h (collectively referred to as loops 242). As previouslydescribed, each of loops 242 a-242 h is produced by cutting slits 241.The application of force F_(p) to tip 44 of tube 25 brings the axialends of slits 241 together such that struts bow and twist outwardly toform loops 242 of proximal side 40 (FIGS. 2G-2H). Central tube 22 may beconstrained during the application of force F_(p). One skilled in theart will recognize that any combination of forces sufficient to reducethe axial length of the tube 25 would be sufficient to deploy theproximal side 40 of occluder 20. As described above for distal side 30,the loops 242 are evenly distributed about central tube 22 and tip 44.Similarly, the angle between radially equally-spaced slits 241 inproximal side 40 is determined by the formula (360/n_(d)) where n_(d) isthe total number of loops 242.

Although the distal side 30 and the proximal side 40 of the occluder 20,shown in FIG. 2H, each include eight loops 232 and 242, respectively,one skilled in the art will recognize that the distal side 30 andproximal side 40 of an occluder 20 according to the present inventionmay include any number of loops 232 and 242, respectively, requiredand/suitable for a given application. Further, although as illustrated,distal side 30 and proximal side 40 both include eight loops, there isno requirement that distal side 30 and proximal side 40 include the samenumber of loops. In fact, in particular applications, it may beadvantageous to use an occluder 20 in which distal side 30 containsfewer loops than proximal side 40, or vice versa.

It will be apparent to one skilled in the art that loops 232 and loops242 do not have to be the same size, although they could be. In oneembodiment, loops 232 are larger in size than loops 242. In anotherembodiment, loops 232 are smaller in size than loops 242. Size of loops232 and 242 is determined by the lengths of slits 231 and 241,respectively. Therefore, absolute and relative lengths of slits 231 and241 can be varied to achieve desired absolute and relative sizes ofloops 232 and 242.

While loops 232 and 242, shown in FIGS. 2F-2H are illustrated asaligned, this does not have to be the case. In one embodiment, loops 232and 242 are radially offset from each other. This can be achieved bymaking cuts to create slits 231 and 241 such that they are radiallyoffset relative to each other. The maximum degree of offset will dependon the number of slits. In general, if slits are equally spaced, themaximum possible offset will be one half of the angle between the loops.For example, if distal side 30 (or proximal side 40) contains 8 slits(and therefore 8 loops), the loops will be 45 degrees apart (see theformula described above), thereby allowing for maximum degree of offsetof one half of 45 degrees, which is 22.5 degrees between loops 232 andloops 242. It is understood, that offset can be in either rotationaldirection (i.e., clockwise and counterclockwise). Therefore, in thisexample with 8 slits, an offset of 30 degrees is equivalent to an offsetof 7.5 degrees in the opposite direction.

The cutting pattern illustrated in FIG. 2E can be varied, as shown inFIGS. 2I-2K. According to one embodiment of the invention, the number ofslits 231 and 241 cut in the tube 25 can be changed according to thedesired number of loops 232 and 242 in the occluder 20 when deployed.The cross-sectional dimensions of loops 232 and 242 are determined bythe thickness of tube 25 and the distance between adjacent slits 231 and241. The length of slits 231 and 241 determines the length of loops 232and 242 and the radial dimensions of the deployed occluder 20. In thismanner, the dimensions of loops 232 and 242 can be controlled duringproduction of occluder 20. For example, as more material is removed fromtube 25 during the cutting process used to form slits 231 and 241, thethickness of loops 232 and 242 decreases. Moreover, any or all of slits231 and 241 can be cut such that thickness of loops 232 and 242 variesalong their length. In some embodiments, it may be desirable to havewider loops 232 and 242 at the location where the loops join tube 25 tocreate a sturdier device. Alternatively, it may be desirable to have awider portion elsewhere along the loops 232 and 242 such that occluder20 is predisposed to bend into a certain shape and arrangement. Forexample, the portion of loops 232 and 242 nearer central tube 22 may bethinner than the portion of loops 232 and 242 nearer end 39 and tip 44,respectively, to facilitate bending of the loops 232 and 242.

Slits 231 and 241, as shown in FIG. 2J, are cut axially along the lengthof tube 25. However, as one of skill in the art will recognize, slits231 and/or 241 may also be cut along other dimensions of tube 25. Forexample, as shown in FIG. 2I, slits 231 and 241 may be cut at an anglesuch that they are helically disposed on tube 25. Angled slits 231 and241 produce angled loops 232 and 242 during deployment. Further, slits231 and 241 need not be straight; for example, slits 231 and 241 may becut as zigzags, S-shaped slits, or C-shaped slits. One skilled in theart will be capable of selecting the angle for the slits 231 and/or 241and the loop 232 and 242 shape(s) appropriate for a given clinicalapplication. For example, when occluder 20 is formed from a polymer tube25, straight loops 232 and 242 may be preferable because they willimpart maximum stiffness to occluder 20. If the tube 25 is formed of astiffer material, the angled slits 231 and/or 241 may provide a moredesired stiffness to the occluder 20.

In one embodiment, the occluder 20 has loops according to FIGS. 2A-2D onone side and loops according to FIGS. 2E-2H on the other side. Forexample, occluder 20 may comprise loops 42 on the proximal side 40 andloops 232 on the distal side 30, or it may comprise loops 242 on theproximal side 40 and loops 32 on the distal side 30.

In one embodiment, for example as shown in FIG. 2H, each loop 242 and232 has some amount of twist, i.e., when the loop is formed, theproximal side of the loop is radially offset with respect to the distalside of the loop. Loops 242 and/or 232, however, need not have anytwist.

FIG. 2M, for example, illustrates an embodiment of the occluder withslits cut as illustrated in FIG. 2L. In this embodiment, neither loops32 nor loops 42 are twisted. It will be apparent to one skilled in theart that any combination of twisted and untwisted loops may be used.Furthermore, an occluder can have any combination of loops withdifferent bends and twists if desired.

In one embodiment, loops 32 (or 232) of distal side 30 are bent to formconcave loops, while loops 42 (or 242) of proximal side 40 are flat(FIG. 11). In this embodiment, the outermost portions of loops 42 (or242) of proximal side 40 oppose the outermost portions of the loops 32(or 232) of the proximal side 30, as described in more detail below,thereby creating a desirable opposing force that secures the occluder 20at its desired location in vivo. So configured, the opposing compressiveforces exerted by sides 30 and 40 on the septal tissue 12 followingdeployment of occluder 20 in vivo is advantageous in certaincircumstances, such as closing certain kinds of PFOs. In anotherembodiment, loops 42 (or 242 of the proximal side 40 are bent, whileloops 32 (or 232) of the distal side 30 are flat. In yet anotherembodiment, loops 42 (or 242) of the proximal side 40 and loops 32 (or232) of the distal side 30 are bent.

Whatever the number and shapes of loops 32 and 42 (or 232 and 242), theloops 32 and 42 (or 232 and 242) may be of varied sizes to facilitatedelivery of occluder 20, e.g. to improve collapsibility of the occluder20 or to enhance its securement at the delivery site. For example, loops32 and 42 (or 232 and 242) that are sized to better conform withanatomical landmarks enhance securement of the occluder 20 to the septaltissue 12 in vivo. As indicated above, the cross-sectional dimensions ofloops 32 and 42 (or 232 and 242) are determined by the thickness of tube25 and the distance between adjacent slits 31 and 41 (or 231 and 241).The length of slits 31 and 41 (or 231 and 241) determines the size ofloops 32 and 42 (or 232 and 242) and the radial extent of the deployedoccluder 20. In at least some embodiments, each of distal side 30 andproximal side 40 has a diameter in the range of about 10 mm to about 45mm, with the particular diameter determined by the size of theparticular defect being treated. In particular embodiments, the diameterof distal side 30 will be different than that of proximal side 40 so asto better conform to the anatomy of the patient's heart.

According to one embodiment of the invention, the loops of the occluderare formed by struts as illustrated in FIG. 2B. Sections 91 a, 91 b, 92a, 92 b, 93 a, 93 b, 94 a, and 94 b are of equal distance, being about ⅓the length of distal side 30 (i.e., the distance between central tube 22and end 39) of the tube 25. According to another embodiment of theinvention, other lengths of sections can be used to produce advantageousresults. In general, the longer the length of the hemispherical struts,such as half sections 91 a, 91 b, 94 a, and 94 b, the stiffer theoccluder will be. The longer the length of the quarter (as shown)struts, such as half sections 92 a, 92 b, 93 a, and 93 b, the less stiffthe occluder will be. In general, the hemispherical cut (one of the two)may be 20-40% of the overall length of the distal side (or proximalside) the tube. Specifically, the hemispherical cuts could be 40% of theoverall length of the distal side (or proximal side) and then thequarter cut could be 20% of the overall length of the distal side (orproximal side) of the tube 25. Also, the lengths of the hemisphericalcuts need not be the same. It may be advantageous to shorten one or theother side of the hemispherical cut based on a desired stiffnesscharacteristic for a particular application of the occluder. In analternative structure, the hemispherical cuts can be extended in a rangeup to 100% of the length of the distal side (or the proximal side) ofthe occluder, while still enabling the bow and twist of the struts.

As indicated previously and shown in FIGS. 2A-2H, distal side 30 andproximal side 40 of occluder 20 are connected by central tube 22. Thecentral tube 22 is formed by the portion of tube 25 between the distalside 30 of tube 25, which contains slits 31, (or 231) and the proximalside 40 of tube 25, which contains slits 41 (or 241). Given that thecentral portion of tube 25 remains uncut during the cutting process, thecentral portion of the tube maintains its profile upon the applicationof forces F_(d) and F_(p) and does not bow and twist outward as theproximal and distal sides are adapted to do.

According to one embodiment, central tube 22 is straight, as illustratedin FIGS. 2D and 2H, where the central tube 22 is perpendicular to loops32 and 42 (or 232 and 242). According to another embodiment of theinvention, central tube 22 is positioned at an angle θ relative to theproximal side 40 of the occluder 20, as shown, for example, in FIGS. 5Band 11. The shape of central tube 22 included in a given occluder is, atleast in part, determined by the nature of the aperture 18. An occluderhaving a straight central tube 22 is particularly suited to treat ananatomical anomaly including a perpendicular aperture, such as an ASD,VSD and certain PFOs. Often, however, anatomical anomalies, such ascertain PFOs, have non-perpendicular apertures and are sometimes quitesignificantly non-perpendicular. An occluder having an angled centraltube 22 is well-suited for treatment of such defects, such that theangle of the anatomical aperture 18 is more closely matched by thepre-formed angle θ of the occluder 20. Also, the length of central tube22 can be varied depending on the anatomy of the defect being closed.Accordingly, the distal side 30 and proximal side 40 of occluder 20 aremore likely to be seated against and minimize distortion to the septaltissue 12 surrounding the aperture 18, as shown in FIG. 13. Awell-seated occluder 20 is less likely to permit blood leakage betweenthe right 11 and left 13 atria, and the patient into which the occluder20 has been placed is, therefore, less likely to suffer embolisms andother adverse events.

Advantageously, angled central tube 22 also facilitates delivery ofoccluder 20 because it is angled toward the end of the delivery sheath.In at least some embodiments, the angle θ is about 0-45 degrees. To formthe angle θ, proximal side 40 of the occluder 20 bends depending upon,among other factors, the material used to form occluder 20. Accordingly,depending upon design considerations, tip 44 and end 39 may be alignedwith central tube 22 or perpendicular to proximal side 40 or somevariation in between. One skilled in the art will be capable ofdetermining whether a straight or angled central tube 22 is best suitedfor treatment of a given anatomical aperture 18 and the appropriateangle θ, typically in the range between about 30 and about 90 degrees.Sometimes, angles of about 0 degrees to about 30 degrees can be used inan oblique passageway such as a very long tunnel PFO. One skilled in theart will recognize that the concept of an angled central tube may beapplied to septal occluders other than those disclosed herein.

When central tube 22 is positioned at angle θ, distal side 30 andproximal side 40 of occluder 20 may be configured such that they areeither directly opposing or, as shown in FIGS. 5B, 11 and 12, offset bydistance A. One skilled in the art will, of course, recognize that theshape and arrangement of either or both of distal side 30 and proximalside 40 may be adjusted such that the compressive forces they apply areas directly opposing as possible. However, in some clinicalapplications, an occluder 20 having an offset of distance A may beparticularly desirable. For example, as shown in FIGS. 5B, and 11-12, ifthe septal tissue 12 surrounding aperture 18 includes adisproportionately thick portion (e.g. septum secundum 16 as compared toseptum primum 14), the offset A may be used to seat occluder 20 moresecurely upon septal tissue 12. Moreover, the offset A allows each ofsides 30 and 40 to be centered around each side of an asymmetricaperture 18.

When a central tube 22 at angle θ is included in occluder 20, a markeris required to properly orient the occluder 20 in its intended in vivodelivery location. For example, a platinum wire may be wrapped aroundone of loops 32 or 42 (or one of loops 232 or 242) so as to permitvisualization of the orientation of the occluder 20 using fluoroscopy.Alternatively, other types of markers may be used, e.g. coatings, clips,etc. As one skilled in the art would appreciate, the radiopaque markeror material could be embedded or blended in with the extrudate and thusprovide visibility under fluoroscopy. As will be readily understood byone skilled in the art, the orientation of a non-symmetrical occluder 20during delivery is of great importance. Of course, when anon-symmetrical occluder 20 is used, the periphery of the occluder 20may be configured such that the clamping force applied by the proximalside 40 is directly opposed to that applied by the distal side 30.

Upon deployment in vivo (a process described in detail below), anoccluder 20 according to the present invention applies a compressiveforce to the septal tissue 12. Distal side 30 is seated against theseptal tissue 12 in the left atrium 13, central tube 22 extends throughthe aperture 18, and proximal side 40 is seated against the septaltissue 12 in the right atrium 11. At least some portion of each of loops32 and 42 (or 232 and 242) contacts septal tissue 12. In particularembodiments, a substantial length of each of loops 32 and 42 (or 232 and242) contacts septal tissue 12. As illustrated in the representativeFigures, the proximal side 40 and distal side 30 of occluder 20 overlapsignificantly, such that the septal tissue 12 is “sandwiched” betweenthem once the occluder 20 is deployed. According to at least someembodiments and depending upon the material used to form occluder 20,the loops 32 and 42 (or 232 and 242) provide both a radially-extendingcompressive force and a circumferential compressive force to septaltissue 12. In these embodiments, the compressive forces are more evenlyand more widely distributed across the surface of the septal tissue 12surrounding the aperture 18 and, therefore, provide the occluder 20 withsuperior dislodgement resistance as compared to prior art devices. Asused in this application, “dislodgement resistance” refers to theability of an occluder 20 to resist the tendency of the force applied bythe unequal pressures between the right 11 and left 13 atria (i.e. the“dislodging force”) to separate the occluder 20 from the septal tissue12. Generally, a high dislodgement resistance is desirable.

Loops 32 and 42 (or 232 and 242) are also configured to minimize thetrauma they inflict on the septal tissue 12 surrounding aperture 18.Specifically, as indicated previously, the outer perimeter of loops 32and 42 (or 232 and 242) may be rounded.

According to one embodiment of the invention, for example, asillustrated in FIGS. 2B-2D, the circumferential portions of loops 32 and42 are thinner than the orthogonally-extending portions of loops 32 and42; therefore, the center of the occluder 20 is stronger than itsperimeter. Accordingly, outer perimeter of loops 32 and 42 of occluder20 has a low compression resistance. As used in this application,“compression resistance” refers to the ability of an occluder 20 toresist the lateral compressive force applied by the heart as itcontracts during a heartbeat. Generally, an occluder that resistscompressive force, i.e. has high compression resistance, is undesirablebecause its rigid shape and arrangement may cause trauma to the septaltissue 12, the right atrium 11, and/or the left atrium 13.

According to at least some embodiments of the present invention,occluder 20 further includes a catch system, generally indicated at 131,that secures the occluder 20 in its deployed state. The catch system131, in general, maintains the shape and arrangement of loops 32 and 42(or 232 and 242) of occluder 20, once the occluder 20 has been deployed.Catch system 131 reduces and maintains the axial length of the occluder20 so that occluder 20 maintains its deployed state, is secured in theaperture 18, and consistently applies a compressive force to septaltissue 12 that is sufficient to close aperture 18. Catch system 131 isparticularly advantageous when the occluder 20 is formed of a polymericmaterial, as previously described, because the polymeric occluder 20 maybe deformed during delivery such that it may not fully recover itsintended shape once deployed. By reducing and maintaining the axiallength of occluder 20 once it has been deployed in vivo, catch system131 compensates for any undesirable structural changes suffered byoccluder 20 during delivery. In some embodiments, catch system 131includes a ceramic material or a material selected from the groupconsisting of metals, shape memory materials, alloys, polymers,bioabsorbable polymers, and combinations thereof. In particularembodiments, the catch system may include nitinol or a shape memorypolymer. Further, the catch system may include a material selected fromthe group consisting Teflon-based materials, polyurethanes, metals,polyvinyl alcohol (PVA), extracellular matrix (ECM) or otherbioengineered materials, synthetic bioabsorbable polymeric scaffolds,collagen, and combinations thereof.

Catch system 131 may take a variety of forms, non-limiting examples ofwhich are provided in FIGS. 6A-6E. For example, as shown in FIG. 6A,catch system 131 includes two catch elements, e.g., balls, 133 and 135,connected by wire 134. The catch system and catch element are preferablymade of the same material as the occluder, although based on designselection, they could be made of the same or different material. Incertain circumstances, it may be necessary to make them of differentmaterial. As illustrated in FIG. 6A, delivery string 137 is attached toball 133 and is then extended through end 39, distal portion 30 of tube25, central tube 22, proximal portion 40 of tube 25, and tip 44, suchthat ball 133 is located between central tube 22 and end 39 and ball 135is located on the distal side of central tube 22. The function of catchsystem 131 is shown in FIGS. 6B-6E. Ball 133 is designed such that, uponthe application of sufficient pulling force F₁ to delivery string 137,it passes through central tube 22 (FIG. 6B) and tip 44 (FIG. 6C). Ball133 cannot reenter tip 44 or central tube 22 without the application ofa sufficient, additional force. In this manner, ball 133 may be used tobring together the distal side 30 and the proximal side 40, therebyreducing and maintaining the axial length of occluder 20. Obviously,during the application of pulling force F₁, the tip 44 of occluder 20must be held against an object, such as a delivery sheath. Ball 135 isdesigned such that, upon application of sufficient pulling force F₂ todelivery string 137, it passes through end 39 (FIG. 6D) and central tube22 (FIG. 6E). The pulling force F₂ required to move ball 135 through end39 and central tube 22 is greater than the pulling force F₁ required tomove ball 133 through central tube 22 and tip 44. However, ball 135cannot pass through tip 44. Thus, the application of sufficient pullingforce F₂ to ball 135 releases distal side 30 and proximal side 40, asdescribed in more detail below. It should be noted that while catchelements 133 and 135 are illustrated as spherical elements in FIGS.6A-6E, catch elements 133 and 135 may take any suitable shape. Forexample, catch elements 133 and 135 may be conical. The narrow portionsof conical catch elements 133 and 135 point toward tip 44 of proximalside 40. One possible mode of recovery or retrieval for this device issimply reversing the implantation procedure. Of course, other modes ofrecovery or retrieval are possible, some of which are described in thisspecification.

A different system for securing the device in the deployed state isshown in FIGS. 7A-7C. A locking mechanism 191 includes a hollow cylinder141 having at least two half-arrows 143 and 145 located at its proximalend (FIG. 7A). Cylinder 141 enters tip 44 under application of pullingforce F₁ to delivery string 137. As cylinder 141 enters tip 44,half-arrows 143 and 145 are forced together such that the diameter ofthe proximal end of cylinder 141 is reduced (FIG. 7C). Under continuedapplication of pulling force F₁, half-arrows 143 and 145 pass throughtip 44 and expand to their original shape and arrangement (FIG. 7B).Given that half-arrows 143 and 145 extend beyond the diameter of tip 44,the axial length of an occluder 20 including the locking mechanism 191shown in FIGS. 7A-7C is maintained in its reduced state. If the implantneeds to be removed or repositioned, the locking mechanism 191 shown inFIGS. 7A-7C may be released by moving half-arrows 143 and 145 togethersuch that the diameter of the proximal end of cylinder 141 is smallerthan that of tip 44 and cylinder 141 passes through tip 44. Cylinder 141may then be withdrawn from tip 44.

One skilled in the art will recognize that catch system 131 may assumenumerous configurations while retaining its capability to reduce andmaintain the axial length of occluder 20 such that occluder 20 maintainsits deployed state. For example, catch system 131 may include a threadedscrew, a tie-wrap, or a combination of catch systems 131. Furthermore,catch system 131 may include multiple members that may provide a steppeddeployment process. For example, catch system 131 as depicted in FIGS.6A-6E may include three balls. In this configuration, one ball is usedto secure the distal end 30 of occluder 20 and another ball is used tosecure the proximal end 40 of occluder 20, and the third ball is securedto the distal end. Any suitable catch system 131 may be incorporatedinto any of the embodiments of occluder 20 described herein. One skilledin the art will be capable of selecting the catch system 131 suitablefor use in a given clinical application.

Occluder 20 may be modified in various ways. According to someembodiments of the present invention, distal side 30 and/or proximal 40side of occluder 20 may include a tissue scaffold. The tissue scaffoldensures more complete coverage of aperture 18 and promotes encapsulationand endothelialization of septal tissue 12, thereby further encouraginganatomical closure of the septal tissue 12. The tissue scaffold may beformed of any flexible, biocompatible material capable of promotingtissue growth, including but not limited to polyester fabrics,Teflon-based materials, ePTFE, polyurethanes, metallic materials,polyvinyl alcohol (PVA), extracellular matrix (ECM) or otherbioengineered materials, synthetic bioabsorbable polymeric scaffolds,other natural materials (e.g. collagen), or combinations of theforegoing materials. For example, the tissue scaffold may be formed of athin metallic film or foil, e.g. a nitinol film or foil, as described inUnited States Patent Publ. No. 2003/0059640 (the entirety of which isincorporated herein by reference). In those embodiments, where occluder20 includes a tissue scaffold, the scaffold may be located on theoutside the face of distal side 30 and proximal side 40 of the occluder,with an alternative of including scaffold also inside the face of distalside 30 and proximal side 40 of the occluder. Also, the tissue scaffoldcould be disposed against the tissue that is sought to be occluded, suchas the septal tissue 12 so that the proximity of the tissue scaffold andseptal tissue 12 promotes endothelialization. Loops 32 and 42, (or 232and 242), can be laser welded, ultrasonically welded, thermally welded,glued, or stitched to the tissue scaffold to securely fasten thescaffold to occluder 20. One skilled in the art will be able todetermine those clinical applications in which the use of tissuescaffolds and/or stitches is appropriate.

Occluder 20 may be further modified so that it lacks end 39 and tip 44,as shown in FIGS. 8A-8C, and, therefore, has a reduced septal profile.Such an occluder may be formed in several ways. For example, accordingto one embodiment, slits 31 and 41 are extended through end 39 and tip44, respectively, of tube 25 during the cutting process. This cuttingpattern produces struts 32 that deform during deployment to produceincomplete loops 32. One side of the device, facing the viewer as shownin FIG. 8A, is formed by slits 31 that extend along the tube 25 tovarying lengths. The tube 25 is cut in half to form half sections 154 aand 154 b. The half sections 154 a and 154 b are further cut to aproximal distance from the end 39 into quarter sections 155 a, 156 a,155 b, and 156 b. The ends of the quarter sections 155 a and 155 b arejoined at “free ends” 153 to close the loop 32. Similarly, the free endsof quarter sections 156 a and 156 b may be joined by appropriatecutting, see FIG. 8b . The ends may be joined using any suitableconnectors, e.g., 151, e.g., welds. One of skill in the art willrecognize that the free ends 153 of loops 32 may be connected usingother means, including but not limited to seams and bonds obtained byheat or vibration.

In the above embodiment, the slits in the quarter sections are runcompletely through the end of the tube 39. In an alternative embodiment,the end 39 may remain uncut, thereby eliminating the need for a weld tojoin the quarter sections together.

The embodiment illustrated in FIGS. 8A-8C depicts an occluder 20 inwhich both sides are formed according to the above-described design.Alternatively, an occluder 20 according to the present invention mayinclude a hybrid structure, wherein one side is designed according tothe embodiment shown in FIGS. 8A-8C and the other side is designedaccording to other types of structures disclosed in this application.

Occluder 20 may be prepared for delivery to an aperture 18 in any one ofseveral ways. Slits 31 and 41 (or 231 and 241) may be cut such that tube25 bends into its intended configuration following deployment in vivo.Specifically, slits 31 and 41 (or 231 and 241) may be cut to a thicknessthat facilitates the bending and formation of loops 32 and 42 (or 232and 242). Upon the application of forces F_(d) and F_(p), tube 25 bendsinto its intended deployed configuration. Alternatively and/oradditionally, tube 25 formed of a shape memory material may be preformedinto its intended configuration ex vivo so that it will recover itspreformed shape once deployed in vivo. According to at least someembodiments, these preforming techniques produce reliable deployment andbending of occluder 20 in vivo. An intermediate approach may also beused: tube 25 may be only slightly preformed ex vivo such that it ispredisposed to bend into its intended deployed configuration in vivoupon application of forces F_(d) and F_(p).

An occluder 20 as described herein may be delivered to an anatomicalaperture 18 using any suitable delivery technique. For example, distalside 30 and proximal side 40 of occluder 20 may be deployed in separatesteps, or both distal side 30 and proximal side 40 of occluder 20 may bedeployed in the same step. One delivery method will be described indetail herein.

As shown in FIGS. 9A-9H, a delivery sheath 161 containing pusher sleeve(also referred to as a “catheter”) 169 (shown in FIG. 9H) is used todeliver occluder 20 including the catch system 131 illustrated in FIGS.6A-6E. Sheath 161 contains occluder 20 in its elongated, delivery form(FIG. 9A). As shown in FIG. 9B, delivery sheath 161 is first insertedinto the right atrium 11 of the patient's heart. Sheath 161 is nextinserted through aperture 18 located in the septal tissue 12 (which, inthis example, is a PFO tunnel) and into the left atrium 13 (FIG. 9C).Distal side 30 of occluder 20 is then exposed into the left atrium 13,as shown in FIG. 9D. Pulling force F₁ is then applied to delivery string137 while pusher sleeve 169 is holding the occluder 20 in place suchthat ball 133 passes through the central tube 22, thereby securingdistal side 30 into its deployed state (FIG. 9E). Sheath 161 is furtherwithdrawn through the aperture 18 and into the right atrium 11, suchthat central tube 22 is deployed through the aperture 18 (FIG. 9F).Proximal side 40 of occluder 20 is then exposed into the right atrium 11(FIG. 9G), and pulling force F₁ is again applied to delivery string 137while pusher sleeve 169 is holding the occluder 20 in place such thatball 133 passes through tip 44, thereby securing the proximal side 40into its deployed state (FIG. 9H). When properly deployed, occluder 20rests within the aperture 18, and the distal side 30 and proximal side40 exert a compressive force against septum primum 14 and septumsecundum 16 in the left 13 and right 11 atria, respectively, to closethe aperture 18, i.e. the PFO. When occluder 20 is properly deployed,delivery string 137 is detached from catch system 131, including balls133 and 135 and a connecting member, and sheath 161 is then withdrawnfrom the heart. In the event occluder 20 is not properly deployed afterperforming the procedure described above, the occluder 20 may berecovered by reversing the steps of the above described deliverysequence.

In an alternative recovery technique, the occluder 20 may be recoveredand repositioned by catch system 131 as shown in FIGS. 10A-10D. Pushersleeve 169 in sheath 161 is positioned against tip 44 of the occluder 20in the right atrium 11 (FIG. 10A). Pulling force F₂ is applied todelivery string 137, such that ball 135 passes through end 39 and intocentral tube 22, thereby releasing distal side 30 from its deployedstate (FIG. 10B). Force F₂ is again applied to delivery string 137 sothat ball 135 subsequently passes through central tube 22, therebyreleasing proximal side 40 from its deployed state (FIG. 10C). Deliverystring 137 is then pulled further such that occluder 20, now in itselongated state, is retracted into sheath 161 (FIG. 10D). Followingrecovery of occluder 20, sheath 161 may be withdrawn from the heart andanother occluder inserted in the desired delivery location as describedabove and shown in FIGS. 9A-9H.

FIGS. 14A-D illustrate an alternate embodiment of an occluder 1120according to an embodiment of the invention. Like other occluders 20illustrated and described herein, the body of occluder 1120 has anelongated delivery configuration, shown in FIG. 14A and a shorteneddeployed configuration, preferably including loops or petals, shown inFIG. 14D. Occluder 1120 has certain similarities to occluder 20illustrated in FIGS. 2E-2H. Occluder 1120 has a distal end 1139 and aproximal end 1144. Loops 1132 and 1142 are formed in the occluder 1120in a deployed configuration. In one embodiment, the proximal side 40 andthe distal side 30 of occluder 1120 each include eight loops or petals.Different from the embodiment 20 shown in FIGS. 2E-2H, the body ofoccluder 1120 is formed of multiple filaments 1161 extending from theproximal end 1144 to the distal end 1139 and bonded together at theproximal end 1144 and at the distal end 1139, as well as at the centralportion 1122, to define a generally tubular or cylindrical shape in thedelivery configuration. The bonded portions of the filaments 1161 definejoints. Freestanding portions of the filaments 1161 define slit-likeopenings 1131, 1141 that enable the formation of loops 1132 and 1142 inthe deployed configuration. The body of occluder 1120 may in someembodiments include an axial opening.

As shown in FIG. 14B, the occluder 1120 includes eight filaments 1161a-h and eight openings 1131 that form eight extended segments that form,on the distal side 30, the distal loops or petals 1132. As shown in FIG.14B, upon application of force Fd to distal end 1139, extended segmentsdefined by openings 1132 bow and twist outward to form distal petals1132 in distal side 30 of the occluder 1120. One of each of distalpetals 1132 originates from the central portion 1122, while the otherend originates from distal end 39. Proximal petals 1142 a-h may beformed in the proximal portion 40, as shown in FIG. 14C, defined byfilaments 1161 and openings 1141 between central portion 1122 andproximal end 1144. The openings 1131, 1141 and therefore the loops 1132and 1142, and central portion 1122 and proximal end 1144 are defined bythe bonding pattern of the filaments 1161. Proximal petals 1142 can beformed by applying force Fp or a combination of forces sufficient toreduce the axial length of the occluder 1120 thereby allowing openings1141 to bow and twist outward to form proximal petals 1142 in proximalportion 40 of the occluder 20. One end of each of proximal petals 1142originates from central tube 1122, while the other end originates fromproximal tip 1144. In alternate embodiments, rather than forming petals,filaments 1161 bend to define the distal portion and the proximalportion of the device. Also, although eight filaments 1161 are used inthe illustrated embodiment, any suitable number of filaments can be usedas needed to define the desired number of loops or petals. The device1120 can be secured in the deployed configuration using a catch memberas described herein and can be delivered and deployed using delivery anddeployment mechanisms as described herein with reference to occluder 20.

In some embodiments, the term “filament” as used herein refers to anythreadlike or wirelike element. A “filament” as used herein can beformed of any material, such as metal, non-metal, polymer, non-polymer,alloy or any other suitable material. In some embodiments, a filamentcan include suture material. The filaments 1161 may be formed ofbiocompatible metal or polymer but are preferably formed of abioabsorbable polymer. In certain embodiments, the filaments 1161 areformed of a material selected from the group consisting of metals, shapememory materials, alloys, polymers, bioabsorbable polymers, including apolyhydroxyalkanoate, and combinations thereof. In particularembodiments, the filaments 1161 include a shape memory polymer, and morepreferably bioabsorbable shape memory polymer.

One technique for making the device is to align the filaments 1161 intoa cylindrical arrangement and form the appropriate bonds to adjacentfilaments. Occluder 1120 is preferably formed by aligning multiplefilaments in a cylindrical arrangement, and selectively bonding thefilaments at the ends and the central portion, such that extending in anaxial direction a first segment of each filament is bonded to eachadjacent filament, a second segment of each filament is unconnected, athird segment of each filament is connected to each adjacent filament, afourth segment of each filament is unconnected, and a fifth segment ofeach filament is connected to each adjacent filament. Each filament 1161is bonded to the two adjacent filaments 1161 at the distal end, at thecentral portion, and at the proximal end. In each of the bondedsegments, i.e., the distal end 1139, the proximal end 1144 and thecentral portion 1122, each filament 1161 could be individually bonded tothe adjacent filaments or all of the filaments 1161 could be bonded todefine the segment at a single time, for example, by heating thatportion of the filaments. The free segments definelongitudinally-extending openings 1131, 1141 between the filaments 1161in the proximal side 40 and the distal side 30. The connected and freesegments of the filaments 1161 are preferably aligned, such that thedistal openings are aligned with each other and the proximal openingsare aligned with each other, such that the proximal end 1139 and thedistal end 1144 and the central portion 1122 have a cylindrical,tube-like shape. The filaments can be arranged by placing the filaments1161 into a placement device 1170, such as illustrated in FIG. 15, whichincludes holes 1171 in order to hold the filaments 1161 in the correctconfiguration while bonding at the appropriate points. The joints canalso be made by any suitable processes, such as welding, heat ornon-heat adhesive. In addition, the occluder 1170 can be conditioned sothat the it is preformed into its deployed configuration to facilitateimproved delivery and closure.

Occluder 1120 is formed without cutting. Accordingly, occluder 1120 doesnot incorporate cut surfaces. One of skill in the art will appreciatethe a device that does not include cut surfaces will have differentstructural properties and will respond differently to stresses than adevice including cut surfaces. Using filaments to form certainembodiments of the occluder provides several advantages. Each filament1161 can readily be formed to have a desired cross-section, e.g., acircular cross-section or a semi-circular cross-section with roundedouter edges and a flat inside edge. The cross-section of a filament canbe any desired shape. Customizing the shape of the filaments 1161changes the cross-sectional shape of the struts that define the petals1132 and 1142 of the deployed occluder 1120. Different filaments in asingle occluder can have different cross-sections in certainembodiments. One advantage of occluder 1120 is that sharp edges andfriction points are eliminated. Another advantage is that the filaments1161, and in particular, the formation of the petals in the deployedcondition, will not stress the center joint 1122 or the ends 1139, 1144of the occluder 1120. Due to the relative strength of the filaments 1161and the occluder 1120 formed by bonding the filaments, the filaments1161 can be extremely thin and, in particular embodiments, the filaments1161 can comprise sutures. For example, in some embodiments, thefilaments can have thicknesses in the range of about 0.001 to about0.100 inches. Bonding can also be performed in such a way as toreinforce any potential stress concentration points. In certainembodiments, individual filaments 1161 can also be made of differentmaterials.

Another advantage of embodiments formed by filaments 1161 is that, forexample, one or more filaments 1161 can readily be coated with atherapeutic agent, anti-thrombogenic compound, drug, otherpharmaceutical agent, radiopaque agent or other substance prior toforming the occluder 1120. All of the exposed surfaces in the deployedoccluder 1120 could thus readily be coated with a desired substance. Ina tubular occluder 20 formed by cutting slits into a tube, coating thesides of the struts defined by the slits may be more difficult.

One skilled in the art will recognize that the occluders describedherein may be used with anti-thrombogenic compounds, including but notlimited to heparin and peptides, to reduce thrombogenicity of theoccluder and/or to enhance the healing response of the septal tissue 12following deployment of the occluder in vivo. Similarly, the occludersdescribed herein may be used to deliver other drugs or pharmaceuticalagents (e.g. growth factors, peptides). The anti-thrombogenic compounds,drugs, and/or pharmaceutical agents may be included in the occluders ofthe present invention in several ways, including by incorporation intothe tissue scaffold, as previously described, or as a coating, e.g. apolymeric coating, on the tube(s) 25 forming the distal side 30 andproximal side 40 of the occluder 20. Furthermore, the occludersdescribed herein may include cells that have been seeded within thetissue scaffold or coated upon the tube(s) 25 forming the distal side 30and proximal side 40 of the occluder 20.

One skilled in the art will further recognize that occluders accordingto this invention could be used to occlude other vascular andnon-vascular openings. For example, the device could be inserted into aleft atrial appendage or other tunnels or tubular openings within thebody.

Certain embodiments of the present invention have certain similaritiesto devices and/or may be used with a number of delivery and catchsystems such as those described in U.S. application Ser. No. 10/731,547,entitled Septal Closure Devices, filed Dec. 9, 2003; U.S. applicationSer. No. 11/121,833, entitled Catching Mechanisms for Tubular SeptalOccluder, filed May 4, 2005; U.S. application Ser. No. 11/235,661,entitled Occluder Device Double Securement System for Delivery/Recoveryof such Occluder Device, filed Sep. 26, 2005; U.S. application Ser. No.11/384,635, entitled Catch Member for PFO Occluder, filed Mar. 20, 2006;U.S. application Ser. No. 11/644,373, entitled Catch Members forOccluder Devices, filed Dec. 21, 2006; U.S. application Ser. No.11/111,685, entitled Closure Device with Hinges, filed Apr. 21, 2005;U.S. application Ser. No. 11/729,045, entitled Screw Catch Mechanism forPFO Occluder and Method of Use, filed Mar. 28, 2007; U.S. applicationSer. No. 11/729,637, entitled Deformable Flap Catch Mechanism forOccluder Device, filed Mar. 29, 2007; and U.S. application Ser. No.11/904,545, entitled Implant Catheter Attachment Mechanism Using Snareand Method of Use, filed Sep. 27, 2007, all of which have the sameassignee as the present application and are herein incorporated byreference.

Having described preferred embodiments of the invention, it should beapparent that various modifications may be made without departing fromthe spirit and scope of the invention, which is defined in the claimsbelow.

What is claimed is:
 1. A device for occluding a defect in a body, theoccluder comprising: an occluder body that is reconfigurable between anelongated tubular cylindrical delivery configuration and a shorteneddeployed configuration, the occluder body comprising a plurality offilaments, each filament of the plurality of filaments comprising (i) aproximal end portion, (ii), a distal end portion, (iii) a centralportion disposed between the proximal end portion and the distal endportion, (iv) a proximal free segment disposed between the proximal endportion and the central portion, and (v) a distal free segment disposedbetween the central portion and the distal end portion, the proximal endportion of each filament of the plurality of filaments being bondedtogether and aligned to form the proximal end portion and defining agenerally tubular cylindrically shaped joint, the central portion ofeach filament of the plurality of filaments being bonded together andaligned to form the central portion and defining a generally tubularcylindrically shaped joint, and the distal end portion of each filamentof the plurality of filaments being bonded together and aligned to formthe distal end portion and defining a generally tubular cylindricallyshaped joint, wherein, when the occluder body is in the deployedconfiguration, the proximal free segment of each filament of theplurality of filaments forms a proximal loop, and the distal freesegment of each filament of the plurality of filaments forms a distalloop, wherein each of the proximal loops of each filament of theplurality of filaments overlaps with adjacent proximal loops of theplurality of filaments at a discrete location within an occlusiveproximal face formed by the proximal loops, wherein each of the distalloops of each filament of the plurality of filaments overlaps withadjacent distal loops of the plurality of filaments at a discretelocation within an occlusive distal face formed by the distal loops,wherein the occlusive distal face and the occlusive proximal facecooperate to occlude the defect and wherein each filament of theplurality of filaments comprises a discrete wire.
 2. The device of claim1, wherein, when the occluder body is in the delivery configuration,each filament of the plurality of filaments extends generally parallelto a longitudinal axis of the occluder body and the generally tubularshape is a cylindrical shape in the delivery configuration.
 3. Thedevice of claim 1, wherein, when the occluder body is in the deployedconfiguration, each of: (a) the proximal end portion, (b) the centralportion, and (c) the distal end portion are generally coaxially alignedwith a longitudinal axis of the occluder body.
 4. The device of claim 1,further comprising a catch system, wherein the catch system is adaptedto secure the occluder body in the deployed configuration such that theoccluder is not secured during delivery and becomes secured duringdeployment.
 5. The device of claim 1, wherein the occluder furthercomprises tissue scaffolding attached to at least one of the proximalside of the occluder or the distal side of the occluder.
 6. The deviceof claim 1, wherein one or more of the proximal loops of the pluralityof filaments is of different size than one or more of the distal loopsof the plurality of filaments.
 7. The device of claim 1, wherein none ofthe proximal loops of the plurality of filaments and none of the distalloops of the plurality of filaments includes a cut surface.
 8. Thedevice of claim 1, wherein a first filament of the plurality offilaments has a semi-circular cross-section.
 9. The device of claim 1,wherein a first filament of the plurality of filaments and a secondfilament of the plurality of filaments have different cross-sections.10. The device of claim 1, wherein a first filament of the plurality offilaments is coated with a therapeutic agent.